Computer virus is basically a piece of malicious code that is designed to perform some illegal activities on computers that it gets added to. Viruses can control or damage computer systems, use them as tools to attack other computers, use its resources, take victim’s files hostage and demand a ransom, and perform various other activities as well. To put it shortly, the author of the virus decides what is the purpose of the virus. The virus can function entirely without computer owner’s knowledge. Computer viruses are extremely dangerous, especially because the majority of them hides deeply in the computer system and tends to hide their presence.

Computer viruses are divided into different categories depending on their functionality.

Non-malicious software, which can pose a threat to the computer system if the user starts using their services carelessly:

Browser hijackers;

Adware (ad-supported programs);

Rogue anti-spyware.

Dangerous computer viruses that can corrupt computer system install other malicious programs and initiate other illegal activities.

Ransomware;

Trojans;

AOL parasites;

Worms.

Viruses used to spy on the user; the rest of malicious/spyware related computer parasites.

Sniffers;

Network Management Tools;

Remote Administration Tools;

System Tools.

This list does not include other computer viruses that belong to several categories at once. Nowadays, many computer viruses can combine functions of several different computer threats and confuse the computer user. Sometimes, computer parasites have several features that help to deceive anti-virus programs and avoid detection. It is no secret that cybercriminals do everything to keep their malicious tools on victims’ computers and continue to spy on the user, steal information, damage or control the computer entirely.

What can computer viruses do?

Just like we have mentioned before, computer viruses can perform many different functions. There are many more activities that malicious programs can initiate – the imaginary of cyber criminals cannot be measured in any way. Below, we provide a brief list of activities that malicious programs can initiate. Please understand that there are many more activities that malicious programs can start – the imaginary of cyber criminals cannot be measured in any way.

Once installed, a virus can add a malicious script to MBR and damage the computer system before the computer loads.

It can also change hardware configuration, delete CMOS memory and damage BIOS. It goes without saying that computer that gets these settings adjusted in a bad way fails to function properly and certain data kept on the computer can be lost forever.

Delete, corrupt, overwrite personal files. Despite the danger of data loss, you might also lose access to the computer. If the virus affects the wrong data, the computer might fail to boot.

Download and install other malware examples, such as worms, trojans, backdoors, ransomware, and the like. Some viruses are designed to stay silently on compromised computers and show no signs of existence, but after some time, they download malware from a remote server and cause damage the computer system.

Use the compromised PC as a tool to distribute malicious programs further. Such viruses can use computer’s resources and Internet connection and use numerous techniques to spread malware.

Encrypt files and demand a ransom;

Disguise malicious executive files and other components related to virus as safe records and avoid detection;

Slow down the operating system and cause other functionality and stability-related problems. Steal personal information and use it for malevolent motives;

Create and save loads of useless files to clutter computer’s memory;

Corrupt reputable programs and make them corrupt every file as soon as it gets opened via the compromised program.

How do computers get infected with malicious software?

Computer viruses are meant to be installed with or without user’s intervention, although in most cases the computer user unknowingly does something that allows the virus to enter the computer system. Viruses can be installed while sharing files with other computer users, browsing untrustworthy websites, downloading free files or programs to the system, opening the wrong emails and installing free applications with Default or Standard settings. To avoid malware attacks, follow these simple rules:

Do not trust unknown people that send you emails, especially if these contain some attachments. Untrustworthy emails frequently contain some kind of malware. So please, stay away from Spam, Junk, Trash folders, but do not underestimate emails that reach your Inbox. Just because an email letter went to an inbox, it does not mean that it is safe to interact with it. If you do not know the sender, ignore such messages.

Do not accept offers to install free software updates or “very useful programs” that you have never heard about. If you receive a pop-up saying that you must update Java, otherwise you will not be able to access certain content, do not rush to click “agree.” Java updates must be downloaded from safe sources only.

Viruses can be installed manually, too. Make sure you always leave your PC in a safe place where no one can access it. Scammers can infect your computer just by plugging in a device that contains a malicious virus.

Pirated programs, software cracks, and other suspicious downloads are frequently filled up with unnecessary components that can damage the computer system. Understand that free licensed software is something illegal and cyber criminals tend to take advantage of people who want to get full software versions for free. Do not break the laws or cyber criminals might damage your computer!

Malware can also be installed by other viruses, most frequently – by Trojans. A Trojan horse can remain silent for weeks and then all of the sudden download a malicious program to the system.

Viruses can be installed with the help of exploit kits, too. Exploit kits are hard to understand, but to put it simply, these tools are used to infect computers by exploiting vulnerabilities of Internet browsers, applications such as Java or Adobe Flash, and other software.

What is the best way to uninstall viruses from the system?

Viruses can be semi-dangerous and entirely malicious, however, no matter what kind of a computer virus it is, we do not recommend you to keep such dangerous programs on the computer system. To remove viruses, you should rely only on a trustworthy anti-malware program, and not try to delete virus’ components manually as this can result in failure. To remove computer viruses, we heartily recommend you to use either Reimage, Plumbytes Anti-MalwareWebroot SecureAnywhere AntiVirus, or Malwarebytes Anti Malware. If you want, you can use another reliable malware removal tool, as well.

The most infamous computer viruses of all time

I Love You virus. It is probably one of the most successful computer viruses of all time. It managed to infect over 50 million computers around the globe, and we doubt that any other virus can beat this record. This virus is designed to affect Microsoft Windows computers and is described as a computer worm. It sends malicious emails titled ILOVEYOU including LOVE-LETTER-FOR-YOU.txt.vbs file. The worm could overwrite files, and proliferate itself by sending the malicious e-mail message to all people from victim’s Windows Address Book.

CryptoLocker virus. Ransomware-type virus, which has been isolated in 2014. The virus used to encrypt victims’ files with RSA public-key encryption and ask for a ransom ranging from 100 USD or EUR to 600 USD or Eur. Since CryptoLocky’s project has been shut down, various fake versions showed up, including Crypt0l0cker, CrypTorLocker2015, or Il tuo computer e stato infettato da Cryptolocker!. According to malware researchers, the real CryptoLocker ransomware has earned more or less $3 million just by collecting ransoms from miserable computer users.

Locky virus. Yet another ransomware-type virus, which seems to be uncrackable. This virus is already one of the most successful ransomware examples, although it has been first discovered in 2016 only. Locky’s authors made no mistake and created a virus so powerful that even the most advanced malware researchers cannot find an antidote for victims who have their computers infected with this threat. This virus has released several different variants of itself already, and the latest one is known as ODIN ransomware.

Virus database

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